Worldwide handling our collective excrement there is no one silver bullet. Each person disposes of 1/4 of pound of feces each day and about a quart of urine. Promoting best management practices (BMPs) for these biosolids—also known as sludge--will lessen water pollution and safeguard public health.
Yes it a Herculean issue. No longer do we have the fifth labor of Hercules. Just in one day he cleaned the stable of 3000 cattle for King Augeas breaking two walls and diverting the river through cattle yard that had been there for three decades.
In 2013, with almost 7 billion people worldwide, this amounts to about 400 million metric tons a year. Add to this add 1.4 billion cattle, 19 billion chicken, 1 billion pigs, and 1.8 billion goats and sheep or 14 billion metric tons of animals. This does not include all the wildlife that also adds to this crap. If you address the major public health issue about one third of population (2.5 billion people) lack clean drinking water while 2 million children die every year from diarrhea
One innovation is happening in China. They have over large 173 bio-gas plants and 748 large to medium bio-digesters that handle 20 million metric tons of sewage producing 200 million cubic meters of methane gas. Integrating biosolids into a new resource takes ingenuity and political will
Today over 16,000 sewage treatment facilities serve nearly 190 million Americans (72% percent of the
U.S. population—not counting those with decentralized septic and wastewater systems). In addition, these sewage treatment and collection facilities serve thousands of industrial and commercial establishments.
Roughly eight million dry metric tons of biosolids are annually produced or about 70 pounds per person per year. About 54 percent of these biosolids are land applied as fertilizer or as soil conditioner.
Biosolids range from 70 percent to greater than 98 percent water content. The dry matter in biosolids consists mostly of inert minerals (i.e., sand and silica) or biological materials comprised of fat, protein, fiber and carbohydrates. Biosolids also contain trace amounts of heavy metals and organic chemicals. And, biosolids contain varying levels of metals, pathogenic organisms, vector (e.g., insects and rodents) attractants and odor-causing substances that may be harmful. These metals, organic chemicals and pathogens can pose a threat to human health unless the biosolids are sufficiently processed and properly managed.
Part 503 Biosolid Rule allows land application (spreading) of sewage sludge (also known as sludge) as fertilizer or to condition the soil. There are three main options (each with limitations) to dispose of wastewater and sludge: landfilling, incineration, and land-spreading. The EPA has focused on promoting the use of sludge for land application. In 1993, the EPA published the 503 Sludge Rule setting standards for the use or disposal of sewage
The EPA’s standards have generated controversy in the scientific and agricultural communities, as well as with the general public. Although the 503 Sludge Rule establishes minimum quality standards for biosolids to be land applied, many citizens and scientists question the adequacy of these standards. Some have also proposed more stringent standards, additional source separation and greater pretreatment of contaminants. Various scientists expressed concerns about the effects on humans from contaminants concentrated in the sludge during treatment. Numerous citizens that either work with, or live near, sludge have voiced these same concerns.
Several years ago the EPA Inspector General found: “EPA does not have an effective program for ensuring compliance with the land application requirements of the 503 rules. …While EPA promotes land application, they cannot ensure the public that current land application practices are protective of human health and the environment.”
One promising organization is the Resilience Alliance is a research organization comprised of scientists and practitioners from many disciplines who collaborate to explore the dynamics of social-ecological systems (www.resalliance.org).
Because of the possible health and safety implications if land applications of biosolids are improperly performed, some localities have either banned the practice, or are developing stricter regulations.
In conclusion safe application of biosolids requires assertive pre-treatment pollution prevention, adequate monitoring testing, soil surveys, screening of the application area so as to safeguard contamination to water resources and other measures to insure that sludge does not impact public health or the environment.
The debate will continue as to how serious are the risks in the land applications of biosolids. Once we learn to better emulate nature we will prosper since all ecosystems have three things: producers, consumers and decomposers. Let's invest in many viable forms of composting to regain this mismanaged resource
* Certain facts come from- Origin of Feces, David Waltner-Toews, ECW Press, 2013